Communication system using geographic position data

ABSTRACT

A wireless communication system employs directive antenna arrays and knowledge of position of users to form narrow antenna beams to and from desired users and away from undesired users to reduce co-channel interference. By reducing co-channel interference coming from different directions, spatial filtering with antenna arrays improves the call capacity of the system. A space division multiple access (SDMA) system allocates a narrow antenna beam pattern to each user in the system so that each user has its own communication channel free from co-channel interference. The position of the users is determined using geo-location techniques. Geo-location can be derived via triangulation between cellular base stations or via a global positioning system (GPS) receiver. The system can be optimized by applying partially adaptive processing algorithms, which are seeded by geo-location data.

RELATED APPLICATIONS

This application is a continuation of International Application NumberPCT/US97/18780 filed on Oct. 10, 1997, which is a continuation-in-partof U.S. Ser. No. 08/729,289 filed on Oct. 10, 1996, and now U.S. Pat.No. 6,512,481 the entire teachings of which are both incorporated hereinby reference in their entirety.

BACKGROUND OF THE INVENTION

At present, the communications spectrum is at a premium, with projectedhigh capacity requirements of Personal Communication Systems (PCS)adding to the problem. Although all modulation techniques for wirelesscommunications suffer capacity limitations due to co-channelinterference, spread spectrum, or Code Division Multiple Access (CDMA),is a modulation technique which is particularly suited to take advantageof spatial processing to increase user capacity. Spread spectrumincreases signal bandwidth from R (bits/sec) to W (Hz), where W>>R, somultiple signals can share the same frequency spectrum. Because theyshare the same spectrum, all users are considered to be co-channelinterferers. Capacity is inversely proportional to interference power,so reducing the interference increases the capacity.

Some rudimentary spatial processing can be used to reduce interference,such as using sector antennas. Instead of using a single omnidirectionalantenna, three antennas each with a 120 degree sector can be used toeffectively reduce the interference by three, because, on average, eachantenna will only be looking at ⅓ of the users. By repeating thecommunications hardware for each antenna, the capacity is tripled.

Ideally, adaptive antenna arrays can be used to effectively eliminateinterference from other users. Assuming infinitesimal beamwidth andperfect tracking, adaptive array processing (AAP) can provide a unique,interference-free channel for each user. This example of space divisionmultiple access (SDMA) allows every user in the system to communicate atthe same time using the same frequency channel. Such an AAP SDMA systemis impractical, however, because it requires infinitely many antennasand complex signal processing hardware. However, large numbers ofantennas and infinitesimal beamwidths are not necessary to realize thepractical benefits of SDMA.

SDMA allows more users to communicate at the same time with the samefrequency because they are spatially separated. SDMA is directlyapplicable to a CDMA system. It is also applicable to a time divisionmultiple access (TDMA) system, but to take full advantage of SDMA, thisrequires monitoring and reassignment of time-slots to allow spatiallyseparated users to share the same time-slot simultaneously. SDMA is alsoapplicable to a frequency division multiple access (FDMA) system, butsimilarly, to take full advantage of SDMA, this requires monitoring andreassignment of frequency-slots to allow spatially separated users toshare the same frequency band at the same time.

In a cellular application, SDMA directly improves frequency re-use (theability to use the same frequency spectrum in adjoining cells) in allthree modulation schemes by reducing co-channel interference betweenadjacent cells. SDMA can be directly applied to the TDMA and FDMAmodulation schemes even without re-assigning time or frequency slots tonull co-channel interferers from nearby cells, but the capacityimprovement is not as dramatic as if the time and frequency slots arere-assigned to take full advantage of SDMA.

SUMMARY OF THE INVENTION

Instead of using a fully adaptive implementation of SDMA, exploitationof information on a users' position changes the antenna beamforming froman adaptive problem to deterministic one, thereby simplifying processingcomplexity. Preferably, a beamformer uses a simple beam steeringcalculation based on position data. Smart antenna beamforming usinggeo-location significantly increases the capacity of simultaneous users,but without the cost and hardware complexity of an adaptiveimplementation. In a cellular application of the invention, using anantenna array at the base station (with a beamwidth of 30 degrees forexample) yields an order of magnitude improvement in call capacity byreducing interference to and from other mobile units. Using an antennaarray at the mobile unit can improve capacity by reducing interferenceto and from other cells (i.e., improving frequency reuse). Forbeamforming, the accuracy of the position estimates for each mobile userand update rates necessary to track the mobile users are well within thecapabilities of small, inexpensive Global Positioning System (GPS)receivers.

In general, the present invention is a communication system with aplurality of users communicating via a wireless link. A preferredembodiment of the invention is a cellular mobile telephone system. Eachuser has a transmitter, receiver, an array of antennas separated inspace, a device and method to determine its current location, hardwareto decode and store other users' positions, and beamformer hardware. Thebeamformer uses the stored position information to optimally combine thesignals to and from the antennas such that the resulting beam pattern isdirected toward desired users and away from undesired users.

An aspect of the invention uses a deterministic direction findingsystem. That system uses geo-location data to compute an angle ofarrival for a wireless signal. In addition, the geo-location data isused to compute a range for the wireless signal. By using the determinedangle of arrival and range, a system in accordance with the inventioncan deterministically modify the wireless signal beam betweentransceivers.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention, including various novel details of construction andcombination of parts will be apparent from the following more particulardrawings and description of preferred embodiments of the communicationsystem using geographic position data in which like referencescharacters refer to the same parts throughout the different views. Itwill be understood that the particular apparatus and methods embodyingthe invention are shown by way of illustration only and not as alimitation of the invention, emphasis instead being placed uponillustrating the principles of the invention. The principles andfeatures of this invention may be employed in various and numerousembodiments without departing from the scope of the invention.

FIG. 1 is a schematic diagram of a cellular communication system.

FIG. 2 is a schematic block diagram of components in a base station anda mobile unit of FIG. 1.

FIG. 3 is a schematic diagram of a general adaptive antenna array.

FIG. 4 is a schematic diagram of a mobile-to-base communications link incellular communications using AAP SDMA.

FIG. 5 is a schematic diagram of a base-to-mobile communications link incellular communications using AAP SDMA.

FIG. 6 is a schematic diagram of a general SDMA communications systememploying geo-location techniques.

FIG. 7 is a schematic block diagram of two communicating users of FIG.6.

FIG. 8 is a flow chart of a method of operating a cellular telephonesystem using geo-location data.

FIG. 9 is a schematic diagram of a cellular telephone system usinggeo-location data.

FIG. 10 is a schematic block diagram of a steering circuit.

FIG. 11 is a schematic block diagram of a nulling circuit.

FIG. 12 is a schematic block diagram of a receiver module for a mobileunit beamformer.

FIG. 13 is a schematic block diagram of a transmitter module for amobile unit beamformer.

FIG. 14 is a schematic block diagram of a receiver module for a basestation beamformer.

FIG. 15 is a schematic block diagram of a transmitter module for a basestation beamformer.

FIG. 16 is a schematic block diagram of a preferred base stationemploying real-valued FIR filtering at IF.

FIG. 17 is a schematic block diagram of a preferred base stationemploying complex-valued FIR filtering at base band.

FIG. 18 is a schematic block diagram of a beamshaping circuit based onan adaptive-array processing algorithms.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 is a schematic diagram of a general land-based cellular wirelesscommunications system. The geographic area serviced by thiscommunications system 1 is divided into a plurality of geographic cells10, each cell 10 having a respective geographically fixed base station20. Each cell 10 can have an arbitrary number of mobile cellular units30, which can travel between and among the cells 10.

FIG. 2 is a schematic block diagram of components in a base station 20and a mobile unit 30 of FIG. 1. As shown, each base station 20 includesa transceiver 210 having a transmitter 212 and a receiver 214, controlhardware 220, and a set of antennas 25 to communicate with a pluralityof mobile units 30. The mobile units are free to roam around the entiregeographic service area. Each mobile unit 30 includes a transceiver 310having a transmitter 312 and a receiver 314, control hardware 320, ahandset 8, and an antenna or antennas 35 to allow for simultaneoussending and receiving of voice messages to the base station 20. The basestation 20 communicates with a mobile telecommunications switchingoffice (MTSO) 5 to route the calls to their proper destinations 2.

The capacity of a spread spectrum cellular communication system can beexpressed as:

N=(W/R)(N ₀ /E _(b))(1/D)FG

where W is the bandwidth (typically 1.25 MHz);

R is the data rate (typically 9600 bps);

E_(b)/N_(o) is the energy-to-noise ratio (typically 6 dB);

D is the voice duty-cycle (assumed to be 0.5);

F is the frequency reuse (assumed to be 0.6);

G is the number of sectors per cell (assumed to be 1, oromnidirectional); and

N is the number of simultaneous users.

As such, a typical cell can support only about 25-30 simultaneous calls.Space division multiple access (SDMA) techniques can be used to increasecapacity.

The capacity improvement by using an adaptive array at the base station20 in the mobile-base link is summarized below in Table I. The resultsare valid for various antenna beamwidths at a fixed outage probabilityof 10⁻³.

TABLE I Base Station Antenna Beamwidth vs. Call Capability inMobile-to-Base Link Beamwidth (degrees) Capacity (calls/cell) 360 (omni) 31 120  75 60 160 30 320

FIG. 3 is a schematic diagram of an M-element adaptive antenna array andbeamformer. Each element has N adaptive linear filters (ALFs) 55, whereN is the number of users per cell. Each of the ALFs 55 are adapted inreal time to form a beam to and from each mobile unit 30. The ALFs 55use a variety of techniques to form an optimal beam, such as usingtraining sequences, dynamic feedback, and property restoral algorithms.Preferably, the ALFs 55 are single chip adaptive filters as described inU.S. Pat. No. 5,535,150 to Chiang, the teachings of which areincorporated herein by reference.

The M-element array is capable of nulling out M-1 co-channelinterference sources. However, all the users in a CDMA cell share thesame frequency band and therefore, are all co-channel interferers in themobile-to-base link. Because the number of users, N, far exceeds thenumber of antennas, M, subspace methods of direction-of-arrivalestimation are not applicable. Instead, a Constant Modulus Algorithm(CMA) adaptive beamforming approach is more applicable.

For the base-to-mobile link, the co-channel interferers are theneighboring base stations. Conceivably, the number of antennas in theadaptive array at the mobile could be approximately the same as thenumber of neighboring base stations, so subspace methods ofdirection-of-arrival estimation may be applicable to null out theinterfering base stations. The computational complexity of both types ofAAP algorithms is approximately equal.

The majority of the computational complexity incurred by using AAP in acellular system is due to covariance formulation and copy processing.The covariance is a sum of a sequence of matrices, each of which is anouter product of complex array samples. Each term of this outer productis a complex product. The computation requires on the order of K²computations, where K is the number of antennas. Using the covariance,the AAP algorithm computes the antenna weight vector, which is appliedto the received signal vectors. This is a matrix inversion, which copiesthe desired signal. The covariance is updated periodically, and eachdesired signal is copied in real time.

Overall about ½ to ⅔ of the computational complexity incurred by usingAAP SDMA in a cellular system is due to the covariance formulationalone, and the remaining complexity resides in the matrix inversion forcopy weight generation. The complexity, size, power consumption, andcost of implementing AAP SDMA has thus far prevented it from gainingacceptance. In preferred embodiments, the present invention achievessubstantially the same results as a fully adaptive implementation ofSDMA but with significantly less hardware complexity, smaller size,lower power consumption, and lower cost.

FIG. 4 is a schematic diagram of a mobile-to-base communication link ina cellular communications system using AAP SDMA. Illustrated are theantenna array SDMA transmission beam patterns 150 from the mobile units30 to the base station 20 along a central direction 155. Alsoillustrated is interference 170 which would exist without SDMA.

Assuming the base station 20 employs a multi-antenna adaptive arraywhile the mobile unit 30 uses a single omnidirectional antenna, in thereverse channel (uplink, or mobile-to-base), the base station arrayreduces interference from other users both in-cell and out-of-cell, asillustrated in FIG. 4, by pointing its reception beam only towards thedesired mobile unit 30.

For a 120 degree beamwidth, about ⅓ of the mobile units 30 in a cell 10are visible to the array, so the capacity is approximately tripled.Similarly, for a 30 degree beamwidth, about {fraction (1/12)} of themobile units 30 in a cell 10 are visible to the array, so the capacityis increased by a factor of approximately 12.

Assuming that both the base station 20 and the mobile unit 30 employmulti-element antenna arrays, for the reverse channel, this systemsignificantly reduces interference from out-of-cell mobile transmitters,because they are forming beams toward their own base station 20.Ideally, this would improve the frequency reuse, F, from 0.6 to nearly1.0, thereby increasing the capacity by nearly ⅔. Simulations on such asystem show that a frequency re-use factor of F=0.8826 with a 60 degreebeamwidth from the mobile unit improves capacity by 47% over theomnidirectional case (F=0.6).

Improvement due to adaptive arrays on the mobile units 30 are not asdramatic as those achieved with adaptive arrays at the base station 20.In addition, complexity, size, power, and cost can make the applicationof antenna arrays in mobile units 30 impractical for most situations.The reduction in inter-cell interference afforded by adaptive arrays inmobile units 30 may, however, be critical in high-traffic environmentsand for mobile units 30 near the cell boundaries where interference isthe greatest.

FIG. 5 is a schematic diagram of a base-to-mobile communication link ina cellular communications system using AAP SDMA. Assuming the basestation 20 employs a multi-antenna array while the mobile unit 30 uses asingle omnidirectional antenna, in the base-to-mobile link, the basestation 20 antenna array reduces interference to other users bothin-cell 180 and out-of-cell 175, as illustrated in FIG. 4. Results forthis channel for various beamwidths are summarized below in Table II.

TABLE II Base Station Antenna Beamwidth vs. Call Capacity inBase-to-Mobile Channel Beamwidth (degrees) Capacity (calls\cell) 360(omni)  30 75 (5 antennas) 120 55 (7 antennas) 165

Assuming that both the base station 20 and the mobile units 30 employmulti-element adaptive antenna arrays, for the forward channel, thissystem significantly reduces interference from out-of-cell basestations, because the mobile units 30 are forming beams toward their ownbase station 20. As in the reverse channel, ideally, this would improvethe frequency re-use, F, from 0.6 to nearly 1.0, thereby increasing thecapacity by nearly ⅔.

FIG. 6 is a schematic diagram of a general SDMA communications systememploying geo-location techniques. As illustrated, a first user 301 anda second user 302 are in communication. The first user 301 computes thedirection of the desired user 302 and abeam pattern 314 is formed alongthe desired direction 316. In addition to desired users 302, the firstuser 301 wants to avoid projecting a beam in the direction 317 of anundesired user 303. Furthermore, the first user 301 wants to avoidreceiving a beam from any direction other than the desired direction316. These goals are accomplished by utilizing a narrow directionalradio beam.

The radio-beam extends from the transmitting unit at a beamwidth angleB_(o). The distance from the transmitting unit to the receiving unit isdesignated as r_(m). The beamwidth at the receiving unit is B_(m). In acellular system, a base unit is located at the center of a geographicalcell of radius R and the receiving unit is generally mobile and moveswith a velocity V.

FIG. 7 is a schematic block diagram of communicating users of FIG. 6. Asillustrated, the first user 301 and the second user 302 receivegeo-location data from a satellite system 90. The users 301, 302communicate using a respective antenna array 52 controlled by arespective beamformer circuit 34. In addition to the standardtransceiver 310 and control hardware 320, a Global Positioning System(GPS) circuit 350 communicates with a global positioning satellitesystem 90 to command the beamformer 34. Although a satellite system 90is illustrated, the geo-location data can be provided by or derived froma ground-based positioning system. Furthermore, a differential globalpositioning system using both ground and satellite based transmitterscan be employed to provide a higher resolution location.

FIG. 8 is a flow chart of a method of operating a cellular telephonesystem using geo-location data. As a part of the initial establishmentof the wireless link (step 500) between the mobile unit 30 and the basestation 20, the mobile unit 30 must determine its current position. TheGPS receiver may not already be tracking satellites and could takeseveral minutes to get an accurate position estimate (cold start). Ifthe GPS receiver 350 is cold starting (step 510), the base station 20provides a rough location estimate to orient the GPS receiver andsignificantly expedite the position acquisition (step 512). It can sendan estimate of the mobile unit's location via triangularization fromadjacent base stations. This information can be sent along with aChannel Assignment Message (which informs the mobile unit of a TrafficChannel on which to send voice and data) via a Paging Channel. Usersshare the Paging Channel to communicate information necessary for theestablishment of calls.

Then the base station 20 transmits its position to the mobile unit 30via the Paging Channel (Step 520). If the mobile unit 30 is employing adirective antenna array 35′, it uses the base station position and itscurrent position and heading information to form a beam pattern towardthe base station 20 as described above (step 530). The mobile tunes tothe Traffic Channel and starts sending a Traffic Channel preamble andthe current mobile location information to the base station via aReverse Traffic Channel (step 540). Every two seconds, the GPS locationis updated and sent to the base station via the Reverse Traffic Channel.

If the mobile unit 30 is employing a directive antenna array 35′, everytwo seconds it uses the current heading information and compares itsupdated position information to the stored location of the current basestation to update the beam pattern toward the base station. Also, thebase station 20 receives the updated mobile unit location informationand updates it beam pattern toward the mobile unit (step 550). Duringhand-off between base stations (step 560), the directivity of the mobileantenna array, if employed, is disabled (step 570) to allow the user tocommunicate with other base stations.

FIG. 9 is a schematic diagram of a cellular telephone system usinggeo-location data. A preferred embodiment is an implementation of SDMAusing knowledge of user position in a cellular spread spectrumcommunication system. Fixed base stations 20 communicate with rovingmobile units 30 within a prescribed geographic cell 10. Each basestation 20 consists of a transceiver 210, a directional antenna array25′ and associated beamformer hardware 24, control hardware 220, and atransmission link with a mobile telecommunications switching office(MTSO) 5 to route calls. The mobile unit 30 consists of handset 8 with amicrophone and a speaker, a transceiver 310, a GPS receiver 350 (orother hardware to determine position of the mobile), and anomnidirectional antenna 35 or optionally a directional antenna array 35′and associated beamformer hardware 34.

A preferred embodiment of the invention employs a conventional CDMA basestation 20 but with the addition of a 10-element directional antennaarray 25′ capable of forming antenna patterns with a beamwidth of 36degrees, beamformer hardware 24, and additional modems to accommodatethe order of magnitude increase in call capacity. The beamformerhardware 24 takes as input the current latitude and longitude of eachmobile unit, compares it with the known location of the base station 20to determine the angle of arrival (AOA) of each mobile unit's signal,and generates a set of complex antenna weights to apply to each antennaoutput for each mobile unit such that the combined signal represents abeam pattern steered in the direction of the desired mobile unit forboth the transmit and receive signals. The complex antenna weights arecalculated to simply steer the antenna beam.

Instead of calculating the weights in real-time, a set of weights can bestored in a Programmable Read-Only Memory (PROM) for a finite set ofangles of arrival, and can be recalled and immediately applied. The beampattern is preferably widened as the mobile unit 30 approaches the basestation 20 (as described below) because the beam coverage decreases asthe mobile unit 30 approaches the base station 20. Furthermore, theassumption that multipath components propagate from approximately thesame location as the mobile unit 30 becomes less valid as the mobileunit 30 approaches the base station. Optionally, the beamformer hardware24 can track multiple mobile units simultaneously and place nulls oninterfering mobile units, but this is more computationally complex(although not as complex as a fully adaptive array).

The base station antenna array forms an antenna pattern with beamwidthB₀=30 degrees. Assuming the cell radius is R=6 km, the mobile unit is atradius r_(m) (m), the maximum velocity of the mobile unit is V=100(km/h), and the location estimate is updated at U=2 times per second,examination of the pie-slice geometry of the antenna pattern revealsthat the antenna beam width at the mobile unit's location isB_(m)=2πr_(m)(B₀/360) meters, which decreases as the mobile unit 30approaches the base station 20. Once a location estimate has beendetermined for the mobile unit 30 and transmitted to the base station20, the base station 20 forms an antenna pattern with the main lobecentered on the mobile unit 30.

In the worst case, this estimate is wrong by T=30 m. In an update cycle,the mobile travels V/U (m), and as long as this distance is less thanB_(m)/2 (half the beamwidth in meters at the mobile location) minus theerror in the location estimate, T, then the mobile will remain withinthe antenna main lobe: V/U≦(B_(m)/2)−T. Evaluating this equation withthe typical numerical values and solving for the mobile location yieldsr_(m)≧167.6 m at a velocity V=100 km/h. Therefore the mobile unit 30remains in the beam coverage area as long as it is further than 167.6 mfrom the base station 20.

The base station 20 uses the location information to sense when themobile unit 30 is closer than 167.6 m and widens the beam pattern toomnidirectional (or optionally to 120 degrees). This widening does notsignificantly increase interference to other users because the low poweris used for nearby mobile units 30. The complex antenna weights for thewidened beams are preferably stored in memory for a finite set of anglesof arrival, and they can be recalled and immediately applied.

The mobile units 30 include a conventional handset 8 preferablyaugmented with an integrated GPS receiver 350 and modifications to thecontrol logic 320 to incorporate the GPS position data in thetransmission to the base station 20. Mobile units 30 embodied inautomobiles preferably employ a three-element directional antenna array35′ mounted on the automobile and beamformer hardware 34 in addition tothe handset with the built-in GPS receiver as described above. Thebeamformer hardware 34 stores the current base station's latitude andlongitude, compares it with its own current latitude and longitude, andcomputes its current heading via GPS doppler information to determinethe angle of the arrival of the base station signal. A look-up table(for example in a ROM) provides the antenna weights to steer thetransmit and receive beam pattern toward the base station. Optionally,the beamformer hardware can track multiple base stations simultaneouslyand place nulls on interfering base stations.

The necessary accuracy of the mobile position determination depends onthe width of the antenna beam. Assuming the location can be determinedto within a tolerance of T=30 m (i.e., the location can be determinedwith high probability to be within a circle of radius T=30 m), as themobile unit 30 moves, the antenna beam must cover the entire area inwhich the mobile unit 30 can move in the two seconds before the positionis checked again and the antenna beam pattern is updated. Because of thepie-slice geometry of the beam pattern, as the mobile unit 30 approachesthe base station 20, the beam coverage decreases and must be widened tocover the area in which the mobile unit 30 could travel in the twosecond update cycle.

Mobile units employing the antenna array 35′ can form an antenna patternwith beamwidth B₁=120 degrees. Assuming the cell radius is R=6 km, themobile is at radius rm (meters), the maximum rotation of the mobile unitis Ω=45 degrees/second (i.e., the mobile can turn a 90 degree corner in2 seconds), and the location estimate is updated at U=2 times persecond, examination of the pie-slice geometry of the antenna patternyields a location tolerance at the base station of T_(b)=360T/(2πr_(m))(degrees), which increases as the mobile unit 30 approaches the basestation 20.

In addition to location, the mobile unit 30 needs to know its directionof travel so it can determine the orientation of its antenna array. Thisdirection vector can be deduced from GPS doppler data or from a compass.

Once a location estimate has been determined, the mobile unit 30 formsan antenna pattern with the main lobe centered on the base station 20.In the worst case, this estimate is wrong by Tb (degrees) and the mobileunit 30 is turning at maximum rotation Ω=45 degrees/s. In an updatecycle, the mobile's main lobe rotates Ω/U (degrees), and as long as thisangle is less than B₁/2 (half the mobile beamwidth in degrees) minus theerror in the location estimate, Tb (degrees), then the base station 20will remain within the mobile antenna's main lobe, Ω/U≦(B₁/2)−T_(b).Evaluating this equation with the numerical values above and solving forthe mobile location yields r_(m)≧45 m. Therefore the base station 20remains in the beam coverage area as long as it is further than 45 mfrom the mobile unit 30.

The mobile unit 30 uses its location information to sense when it iscloser than 45 m to the base station 20 and widens the beam pattern toomnidirectional. Again, this widening does not significantly increaseinterference to other users because the power transmitted is low. Alook-up table in a ROM provides the antenna weights to change the beampattern to omnidirectional when the mobile unit 30 is within 45 m of thebeam station or during call hand-off when the mobile unit 30 iscommunicating with more than one base station 20.

A preferred embodiment of the invention includes an aspect which reducesinterference and improves capacity as long as the multipath componentspropagate from approximately the same direction as the line-of-sight(LOS) component, which is a fair assumption. Typically, a multipathsignal is limited to a 5-10° arc relative to the receiver. As such,various techniques can be employed to identify and null the multipathcomponent of a received signal.

Aspects of the invention can be practiced even if some users are notequipped with SDMA capability. In the case that a particular user doesnot employ an antenna array, the user will not use position informationand will default to conventional omnidirectional transmission and/orreception. Similarly, in the case that the user does not provideposition information, other users will default to conventionalomnidirectional transmission to and/or reception from that user. Asconventional users are phased out and SDMA equipped users are phased in,the capacity of the system will increase as the fraction of SDMAequipped users increases.

FIG. 10 is a schematic block diagram of a steering circuit. The steeringcircuit 52 includes a GPS receiver 522 connected to a GPS antenna 520for receiving GPS signals from satellites. The GPS receiver 522 computesthe unit's latitude and longitude. A deterministic direction finder 524processes the mobile unit latitude LATM and longitude LNGM data as wellas the base station latitude LATB and longitude LNGB data using a firstlook-up table to compute an angle of arrival (AOA) and a range (RNG)based on the following equations:${AOA} = {\tan^{- 1}\left( \frac{{LNG}_{M} - {LNG}_{B}}{{LAT}_{M} - {LAT}_{B}} \right)}$${RNG} = \sqrt{\left( {{LAT}_{M} - {LAT}_{B}} \right)^{2} + \left( {{LNG}_{M} - {LNG}_{B}} \right)^{2}}$

The AOA and RNG values are processed by a second look-up table in anantenna steering unit 526 which converts the values into antennaweights. The antenna weights are calculated to steer the beam in thedirection of the angle of arrival. That is, the antenna weights becomeunity (i.e., omnidirectional) when the range is below a prescribedthreshold (i.e., the mobile unit is very close to the base station) andfor the mobile unit during handoff. The antenna weights are provided tothe beamformer.

FIG. 11 is a schematic block diagram of a nulling circuit. Position datafrom each user is processed by a GPS circuit 521 _(a), . . . , 521 _(k).For a particular user “a”, a desired latitude LAT_(Ma) and longitudeLNG_(Ma) data are received and for other users undesirable latitudeLAT_(Mb), . . . , LAT_(Mk) and longitude LNG_(Mb), . . . , LNG_(Mk) dataare received. A first look-up table in a deterministic direction finderunit 523 converts the latitude and longitude data from the mobile unitsinto desired AOA_(a) and undesired AOA_(b), . . . , AOA_(k) angles ofarrival and a desired range RNG based on the base station latitudeLAT_(B) and longitude LNG_(B) data. This information for each user ispassed to a second look-up table in a nulling unit 525 which computesantenna weights which are calculated to steer the beam in the directionof the desired angle of arrival AOA_(a) and away from the undesiredangle of arrivals AOA_(b), . . . , AOA_(k) (i.e., a circuit nullsundesired users). The antenna weights can become unity as describedabove. The antenna weights from the nulling unit 525 are provided to thebeamformer.

FIG. 12 is a schematic block diagram of a receiver module for a mobileunit beamformer. The circuit receives a plurality of RF signals IN_(a),IN_(b), IN_(c) over a respective antenna 35′a, 35′b, 35′c of adirectional antenna array 35′. The RF signals are processed into threebaseband signal channels by a three-channel receiver 312. Each basebandsignal is processed by a programmable filter 342 a, 342 b, 342 c. A GPSsignal from a GPS receiver (not shown) is received by a steering/nullingcircuit 344 operating as described above. The steering/nulling circuit344 controls the programmable filters 342 a, 342 b, 342 c. The outputsfrom the programmable filters are combined by a RF combiner 346 toproduce an output signal OUT.

FIG. 13 is a schematic block diagram of a transmitter module for amobile unit beamformer. The input signal IN is split three ways andprocessed by respective programmable filters 341 a, 341 b, 341 c. Theprogrammable filters 341 are controlled by a steering/nulling circuit343 based on inputs from a GPS receiver (not shown) as described above.Three channels of baseband signals result from the programmable filtersand are fed to a three-channel transmitter 314 which sends RF signalsOUT_(a), OUT_(b), OUT_(c) to a respective antenna 35′a, 35′b, 35′c inthe antenna array 35′. In a preferred embodiment of the invention, thesystem implements programmable filtering by including a vector-matrixproduct processing system as described in U.S. Pat. No. 5,089,983 toChiang, the teachings of which are incorporated herein by reference.

FIG. 14 is a schematic block diagram of a receiver module for a basestation beamformer. As illustrated, the antenna array 25′ of the basestation includes 10 antennas 25′₁, . . . ,25′₁₀. The input signals IN₁,. . . ,IN₁₀ are received by a ten-channel receiver 212 which yields tenchannels of baseband signals. Each channel of baseband signal isprocessed by a programmable filter array 242, each of which includes arespective programmable filter for each of N possible users. Theprogrammable filters 242 are controlled by a steering/nulling circuit244 for each user based on GPS data received from each user as describedabove. The outputs from the programmable filters 242 are combined by anRF combiner 246 into N outputs OUT.

FIG. 15 is a schematic block diagram of a transmitter module for a basestation beam former. The transmitter section receives an input signal INwhich is split ten ways into ten channels. Each channel is processed bya programmable filter array 241 having a programmable filter for each Npossible users. The programmable filters are controlled by asteering/nulling circuit 243 for each user based on GPS data from eachmobile user as described above. The programmable filters yield Nbaseband signals divided into ten channels which are transmitted to theantenna array 25′ by a ten-channel transmitter 214. Each antenna 25′₁, .. . ,25′₁₀ receives a respective RF output signal OUT₁, . . . ,OUT₁₀from the transmitter 214.

In a preferred embodiment of the invention, a cellular base stationincludes sufficient signal-processing hardware to support the use ofgeo-location information, received from mobile transmitters, tooptimally shape the receiving antenna-array pattern. This approach is analternative to using a fully adaptive antenna-array that requires asignificantly greater cost in terms of hardware and software.

To implement a fully-adaptive base station receiver, an array of antennainputs must be processed to yield a set of complex-valued weights thatare fed back to regulate the gain and phase of the incoming signals. Theneed for multiple weights applied to a single input signal impliesfrequency independence. The weight or weights are applied to each inputsignal as either a real-valued Finite Impulse Response (FIR) filter at achosen intermediate frequency (IF) (as depicted in FIG. 16 below) or ascomplex-valued FIR filter at base band (as depicted in FIG. 17 below).Following the application of the appropriate weights, the outputs fromeach antenna-channel are summed to yield a beamformed output from thearray.

FIG. 16 is a schematic block diagram of a preferred base stationemploying real-valued FIR filtering at IF. In particular, the basestation 1020 employs a sample-data beam shaping system for downconvertedand band limited signals. The mobile unit 30 communicates with the basestation 1020 through a plurality of N receiver units 1010 ₁, 1010 ₂, . .. 1010 _(N). Each receiver includes a respective antenna 1022 ₁, 1022 ₂,. . . , 1022 _(N). Received signals are transmitted from the antennas1022 ₁, 1022 ₂, . . . 1022 _(N) through a bandpass filter, 1024 ₁, 1024₂, . . . 1024 _(N); a gain controllable amplifier 1026 ₁, 1026 ₂, 1026_(N); a multiplier 1028₁, 1028 ₂, . . . , 1028 _(N); and a secondbandpass filter 1030 ₁, 1030 ₂, . . . 1030 _(N) to form N receiveroutput signals.

The receiver output signals are input to a processing chip 1040 whichincludes a sampling circuit 1042₁, 1042 ₂, . . . , 1042 _(N) and aprogrammable FIR filter 1044 ₁, 1044 ₂, . . . , 1044 _(N) for each inputsignal. The outputs of the FIR filters are summed by a summing circuit1046. A postprocessor 1048 communicates with an off-chip automatic gaincontrol (AGC) circuit 1032 to provide a control signal to the amplifiers1026 ₁, 1026 ₂, . . . , 1026 _(N) to vary the amplifier gains.

The postprocessor 1048 also communicates with an off-chip geo-locationcontroller 1038 which provides geo-location data to a weighted circuit1046. The weighting circuit 1036 provides weights to the on-chipprogrammable filters 1044 ₁, 1044 ₂, . . . , 1044 _(N).

FIG. 17 is a schematic block diagram of a preferred base stationemploying complex-valued FIR filtering at base band. As with FIG. 16,the base station 1020′ includes a plurality of receivers that providesan input signal to a processing chip 1050. The processing chip 1050yields two channels of output to an off-chip postprocessor 1034 whichdecodes, encodes and equalizes the channels. The postprocessor 1034transmits a signal to the AGC circuit 1032 to control the receiveramplifiers 1026 ₁, . . . , 1026 _(N) and is in communication with thegeo-location controller 1038. Geo-location data from the geo-locationcontroller 1038 is processed by a weight-update circuit 1036′ tocalculate weights for a 2N M stage FIR filter array.

The base station includes a beamshaping circuit using a two channeldownconversion system. The processing chip 1050 includes, for each of Nreceivers, a sampling circuit 1052 ₁, . . . , 1052 _(N) and a multiplier1054 ₁, . . . , 1054 _(N). The multipliers 1054 ₁, . . . , 1054 _(N)each provide an in-phase (I) channel 1056 ₁-I . . . , 1056 _(N)-I and aquadrature (2) channel 1056 ₁-Q, . . . , 1056 _(N)-Q. The respectivechannels are passed to respective low pass filters 1058 ₁-I, . . . ,1058 _(N)-Q. Each channel is then down-converted by downconversioncircuit 1060 ₁-I, . . . , 1060 _(N)-Q. The down-converted channels arefed to respective programmable FIR filters 1062 ₁-I, . . . , 1062_(N)-Q. These filters are programmed based on the weight inputs from theweighting circuit 1038. The I and Q channels are individually summed atsumming circuits 1064-I, 1064-Q for output to the postprocessing system1034.

The effect of the weights is to electronically shape the antenna-arrayresponse. Ideally, mobile transmitters that are interfering with thedesired user are suppressed or nulled out, while the transmitter ofinterest is given at least unity gain. Using a fully adaptive antennaarray, the weights are updated with time as the mobile unit moves or aspropagation conditions change. The update of the weights, however, iscomputationally intensive requiring the computation of the covariancematrix of the array response.

In comparison, a preferred base station uses position informationobtained from the mobile transmitter (or from the base-station network)to automatically compute the weights to be applied to the input signalsfrom each antenna. As in the fully-adaptive system, the weights areupdated as the mobile transmitter moves. The potential difficulty withthis approach is that it does not explicitly account for changes in thepropagation conditions between the mobile transmitter and the basestation.

In an effort to characterize the propagation conditions between a mobiletransmitter and a base station, a series of operations were performedusing a fully operational digital-TDMA cellular system. The base stationcomprised 6 receiving antennas that can be located with arbitraryspacings. A single, mobile transmitter is used to characterize thepropagation conditions. Based on the signals received at the basestation, profiles of the signal-propagation delay versus time aremathematically computed. Using these results, the worst caseangle-of-arrival is computed. For this case, the delayed signal isassumed to arrive from a reflector along a line perpendicular to a linejoining the base station and the mobile.

For geo-location-based array-processing to operate, the true location ofthe transmitter is preferably very close to the angle of arrival (AOA)of the primary propagation path from the mobile.

When the true location and the AOA of the primary propagation pathdiffer, the beam pattern produced by geo-location information will notexactly produce the desired gain and nulling of the mobiles' signal.This condition produces suppression of the undesired mobile's signal,but may not completely cancel or null out the transmission.

For worst-case propagation conditions, this implies that theelectronically synthesized beam pattern does not provide the optimalgain for receiving this mobile, nor does it completely null out theundesired signals. The difference between the ideal (fully adaptive)array beam pattern and one constructed using only geo-locationinformation is not too great, however, when the true position of themobile and the AOA of the primary propagation path vary by less than afew degrees.

In practice, the preceding situation occurs when the primary propagationbetween the mobile and the base station are not line-of-sight. Thisoften occurs in urban canyons, where large buildings block line-of-sighttransmission from the mobile to the base station (and vice versa);thereby, placing the mobile's transmission in a “deep fade.” Tocounteract this effect, a preferred base station includes partiallyadaptive array-processing to incrementally refine the initial beampattern that is obtained using only geo-location information. Candidateapproaches for partially-adaptive array processing can be readily foundin the literature for fully-adaptive array processing (e.g., “NovelAdaptive Array Algorithms and Their Impact on Cellular System Capacity,”by Paul Petrus incorporated herein by reference.).

The approaches to computing a mobile's true location have beeninvestigated in detail for CDMA signal communication (see “Performanceof Hyperbolic Position Location Techniques for Code-Division MultipleAccess,” by George A. Mizusawa, incorporated herein by reference).Implementing a GPS receiver in the phone is one candidate for providingaccurate geo-location information to the base station. Alternatively, atleast three base stations can be employed to triangulate the mobilelocation using a variety of algorithms.

FIG. 18 is a schematic block diagram of a beamshaping circuit based onan adaptive-array processing algorithms. As illustrated, the circuitry1080 is essentially identical to that illustrated in FIG. 17. Thepostprocessing circuit, however, communicates with an adaptive-arraymodule 1039 instead of with geo-location data from a mobile unit. Anadaptive-array processing algorithm in the module 1039 provides theweighting signal to the on-chip programmable FIR filters 1062 ₁-I, . . ., 1062 _(N)-Q. The processing chip 1050 can be similarly employed toaccomodate other cellular communication techniques.

Although preferred embodiments of the invention have been described inthe context of a cellular communication system, the principles of theinvention can be applied to any communication system. For example,geo-location data and associated beamforming can be embodied in anyradio frequency communication system such as satellite communicationsystems. Furthermore, the invention can be embodied in acoustic oroptical communication systems.

Equivalents

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims. In particular, the variousaspects of the invention can be embodied in hardware, software orfirmware.

These and all other equivalents are intended to be encompassed by thefollowing claims.

The invention claimed is:
 1. A cellular communication system comprising:a first transceiver at a base station having a first processor and afirst directional antenna; a second transceiver on a mobile unit havinga second processor and a second antenna; a locator on the mobile unitthat determines a physical location of the second antenna; a spatiallymultiplexed communication link formed between the first and secondtransceivers, the link, including a wireless beam from the first antennato the second antenna; and a first adaptive programmable beamformercircuit in the first transceiver that shapes the wireless beam to bedirected between the first antenna and the second antenna, the firstadaptive programmable beamformer circuit having a single integrated chiphaving a plurality of complex multipliers, a plurality of downconversion circuits and a plurality of finite impulse response (FIR)filters programmable with respect to a plurality of weights and asteering circuit that adjusts the plurality of weights to theprogrammable beamformer circuit.
 2. The system of claim 1 wherein thefirst and second antennas are movable relative to one another and thefirst beamformer updates the direction of the wireless beam in responseto the relative motion.
 3. The system of claim 1 wherein the wirelessbeam is a radio frequency beam.
 4. The system of claim 1 wherein thelocator is responsive to location data from a satellite positioningsystem.
 5. The system of claim 1 wherein the locator is responsive tolocation data from a ground-based positioning system.
 6. The system ofclaim 1 wherein the beamformer includes a nulling circuit forsuppressing signals outside of the direction of the second antenna. 7.The system of claim 1 wherein the beamformer includes an adaptiveprocessing module to alter the shape of the wireless beam over time. 8.A cellular communication system comprising: a base transceiver having adirectional base antenna, the base antenna having a fixed geographicalposition within the cell; a mobile transceiver on a mobile unit havingan antenna, the antenna being movable relative to the base antenna; aspatially multiplexed communication link between the base and mobiletransceivers formed by a wireless signal between the antennas; apositioning system on the mobile unit that detects a geographicalposition of the mobile antenna, the position of the mobile antenna beingcommunicated from the mobile transceiver to the base transceiver overthe communication link; an adaptive programmable beamformer circuit inthe base transceiver that modifies the signal in response to therelative motion of the antennas, the adaptive programmable beamformercircuit having a single integrated chip having a plurality of complexmultipliers, a plurality of down conversion circuits and a plurality offinite impulse response (FIR) filters programmable with respect to aplurality of weights and a steering circuit that adjusts the pluralityof weights to the programmable beamformer circuit; and a nulling modulecoupled to the beamformer that suppresses interference to the signal. 9.The system of claim 8 wherein the beamformer updates the shape of thesignal over time.
 10. The system of claim 8 wherein the signal is aradio frequency beam.
 11. The system of claim 8 wherein the positioningsystem is responsive to position data from a satellite positioningsystem.
 12. The system of claim 8 wherein the positioning system isresponsive to position data from a ground-based positioning system. 13.The system of claim 8 wherein the beamformer includes a plurality ofprogrammable filter arrays.
 14. The system of claim 8 further comprisinga table of stored antenna weights stored in memory, the table accessedby the nulling module to modify the signal.
 15. The system of claim 8further comprising an adaptive processing module to alter the shape ofthe beam over time.
 16. The system of claim 8 wherein the mobile antennais a directional antenna.
 17. A method for operating a communicationsystem comprising: operating a first transceiver at a base station andhaving a first processor and a first directional antenna; operating asecond transceiver on a mobile unit having a second processor and asecond antenna; determining the physical location of the second antennarelative to the first antenna; forming a spatially multiplexedcommunication link between the first and second transceivers, the linkincluding a wireless beam between the first antenna and the secondantenna; and in a first adaptive programmable beamformer integratedcircuit chip in the first transceiver, responding to the physicallocation of the second antenna, by using a plurality of complexmultipliers, a plurality of down conversion circuits and shaping thewireless beam using a plurality of programmable finite impulse response(FIR) filters with respect to a plurality of weights and steering thebeam to be directed between the first antenna and the second antennausing the programmable beamformer circuit.
 18. The method of claim 17further comprising the steps of: moving the first and second antennasrelative to one another; and in the beamformer, updating the directionof the signal over time in response to the relative movement.
 19. Themethod of claim 17 wherein the first wireless beam is a radio frequencybeam.
 20. The method of claim 19 wherein the second transceiver in amobile unit may function as the first transceiver and the firsttransceiver in a base station may function as the second transceiver.21. The method of claim 17 wherein the locator is responsive to positiondata from a satellite positioning system.
 22. The method of claim 17wherein the locator is responsive to position data from a ground-basedpositioning system.
 23. The method of claim 17 wherein the beamformerincludes a nulling circuit to suppress signals outside the direction ofthe second antenna.
 24. The method of claim 17 wherein the beamformerincludes an adaptive processing module for altering the shape of thewireless beam over time.
 25. A method of operating a cellularcommunication system comprising: operating a base transceiver having adirectional base antenna, the base antenna having a fixed geographicalposition within a cell; operating a mobile transceiver on a mobile unithaving an antenna, the antenna being movable relative to the basetransceiver; forming a spatially multiplexed communication link betweenthe base and mobile transceivers by a wireless signal between theantennas; in a positioning system on the mobile unit, detecting thegeographical position of the mobile antenna, the position of the mobileantenna being communicated to the base transceiver over thecommunication link; in an adaptive programmable beamformer circuit inthe base transceiver, modifying the signal in response to the relativemotion of the antennas using a single integrated chip having a pluralityof complex multipliers, a plurality of down conversion circuits andshaping the signal using a plurality of finite impulse response (FIR)filters programmable with respect to a plurality of weights, andsteering the signal using the programmable beamformer circuit; and in anulling module coupled to the beamformer, suppressing interference withthe signal.
 26. The method of claim 25 wherein the step of modifying thesignal comprises updating the direction of the signal over time inresponse to relative motion between the antennas.
 27. The method ofclaim 25 wherein the signal is a radio frequency beam.
 28. The method ofclaim 25 wherein the step of detecting comprises receiving position datafrom a satellite positioning system.
 29. The method of claim 25 whereinthe step of detecting comprises receiving position data from aground-based positioning system.
 30. The method of claim 25 wherein thebeamformer includes a plurality of programmable filter arrays.
 31. Themethod of claim 25 wherein the step of modifying the signal comprisesproviding antenna weights from a table stored in memory.
 32. The methodof claim 25 wherein the step of modifying includes adaptively alteringthe shape of the signal over time.
 33. The method of claim 25 whereinthe mobile antenna is a directional antenna.
 34. The method of claim 25wherein the step of forming a communication link comprises spatiallymultiplexing the signal within the cell.
 35. A cellular communicationsystem comprising: a base transceiver having a directional base antenna,the base antenna having a fixed geographical position; a mobiletransceiver on a mobile unit having a directional antenna, the antennabeing movable relative to the base transceiver a spatially multiplexedcommunication link between the base and mobile transceivers formed by awireless signal between the antennas; a positioning system on the mobileunit that detects the geographical position of the mobile antenna, theposition of the mobile antenna being communicated to the basetransceiver over the communication link; and a first adaptiveprogrammable beamformer circuit in the base transceiver and a secondprogrammable beamformer circuit in the mobile transceiver for modifyingthe signal in response to the relative motion of the antennas, the firstand second programmable circuits each having a single integrated chiphaving a plurality of complex multipliers, a plurality of downconversion circuits and a plurality of finite impulse response (FIR)filters programmable with respect to a plurality of weights and asteering circuit that adjusts the plurality of weights to the first andsecond programmable beamformer circuit.
 36. The system of claim 35wherein the beamformers update the direction of the signal over time inresponse to the relative movement between the antennas.
 37. The systemof claim 35 wherein the beamformers modify the signal to beomnidirectional when the antennas are separated by less than a specificrange.
 38. The system of claim 35 wherein the signal is a radiofrequency beam.
 39. The system of claim 35 wherein the positioningsystem is responsive to position data from a satellite positioningsystem.
 40. The system of claim 35 wherein the positioning system isresponsive to position data from a ground-based positioning system. 41.The system of claim 35 wherein the beamformers include a plurality ofprogrammable filter arrays.
 42. The system of claim 35 furthercomprising a table stored in memory for providing antenna weights to thebeamformer to modify the signal.
 43. The system of claim 35 furthercomprising an adaptive processing module coupled to the beamformer toalter the shape of the signal over time.
 44. The system of claim 35further comprising a nulling module coupled to the beamformer tosuppress interference with the signal.
 45. A method of operating acellular communication system comprising: operating a base transceiverhaving a directional base antenna, the base antenna having a fixedgeographical position within a cell; operating a mobile transceiver on amobile unit having a directional antenna, the antenna being movablerelative to the base antenna; forming a spatially multiplexedcommunication link between the base and mobile transceivers by awireless signal between the antennas; in a positioning system on themobile unit, detecting the geographical position of the mobile antenna,the position of the mobile antenna being communicated to the basetransceiver over the communication link; and in a first adaptiveprogrammable beamformer integrated circuit chip in the base transceiverand a second programmable beamformer integrated circuit chip in themobile transceiver, modifying the signal in response to the relativemotion of the antennas by using a plurality of complex multipliers, aplurality of down conversion circuits and shaping the wireless signalusing a plurality of finite impulse response (FIR) filters programmablewith respect to a plurality of weights, and steering the wirelesssignal.
 46. The method of claim 45 wherein the step of modifying thesignal comprises updating the direction of the signal over time inresponse to the relative movement of the antennas.
 47. The method ofclaim 45 wherein the step of modifying comprises determining the rangebetween the base antenna and the mobile antenna and, when the range isless than a specific range, modifying the signal to be omnidirectional.48. The method of claim 45 wherein the signal is a radio frequency beam.49. The method of claim 45 wherein the step of detecting comprisesreceiving position data from a satellite positioning system.
 50. Themethod of claim 45 wherein the step of detecting comprises receivingposition data from a ground-based positioning system.
 51. The method ofclaim 45 wherein the beamformers include a plurality of programmablefilter arrays.
 52. The method of claim 45 wherein the step of modifyingthe signal comprises providing antenna weights from a table stored inmemory.
 53. The method of claim 45 wherein the step of modifying thesignal comprises performing adaptive processing to alter the shape ofthe signal over time.
 54. The method of claim 45 wherein the step ofmodifying the signal comprises suppressing interference with the signalin a nulling module.
 55. The method of claim 45 wherein the step offorming the communication link comprises a spatially multiplex signal.56. A beamforming circuit for a communication system comprising: aplurality of sampling circuits for receiving communication signals; aplurality of programmable finite impulse response (FIR) filters, eachFIR filter being connected to a sampling circuit; a summing circuit thatsums filtered signals from the plurality of FIR filters; and adirectional wireless signal formed from the summed signals.
 57. Thecircuit of claim 56 wherein the sampling circuits, the plurality ofprogrammable FIR filters and the summing circuit are formed on a singleintegrated circuit.
 58. The circuit of claim 56 further comprising amultiplier connected to each sampling circuit to generate an in-phasechannel and a quadrature channel, each channel being connected to afilter, a converter and one of the FIR filters.
 59. The circuit of claim56 wherein the communication system comprises a cellular networkincluding a plurality of transceivers that communicate by wireless linkwith mobile transceiver units, and further including a base stationhaving an adaptive array processor providing weighting signals to theFIR filters.
 60. The system of claim 1 wherein the beamformer furthercomprises: a plurality of sampling circuits for receiving communicationsignals; and a summing circuit that sums filtered signals from theplurality of FIR filters; and a signal representative of a directionalwireless signal formed from the summed signals.
 61. The system of claim60 wherein the sampling circuits, the plurality of programmable FIRfilters and the summing circuit are formed on a single integratedcircuit.
 62. The system of claim 60 further comprising a multiplierconnected to each sampling circuit to generate an in-phase channel and aquadrature channel, each channel being connected to a filter, aconverter and one of the FIR filters.
 63. The system of claim 60 whereinthe communication system comprises a cellular network including aplurality of transceivers that communicate by wireless link with mobiletransceiver units, and further including a base station having anadaptive array processor providing weighting signals to the FIR filters.64. The system of claim 8 wherein the beamformer further comprises: aplurality of sampling circuits for receiving communication signals; anda summing circuit that sums filtered signals from the plurality of FIRfilters; and a signal representative of a directionless wireless signalformed from the summed signals.
 65. The system of claim 64 wherein thesampling circuits, the plurality of programmable FIR filters and thesumming circuit are formed on a single integrated circuit.
 66. Thesystem of claim 64 further comprising a multiplier connected to eachsampling circuit to generate an in-phase channel and a quadraturechannel, each channel being connected to a filter, a converter and oneof the FIR filters.
 67. The system of claim 64 wherein the communicationsystem comprises a cellular network including a plurality oftransceivers that communicate by wireless link with mobile transceiverunits, and further including a base station having an adaptive arrayprocessor providing weighting signals to the FIR filters.
 68. The systemof claim 35 wherein the beamformer further comprises: a plurality ofsampling circuits for receiving communication signals; and a summingcircuit that sums filtered signals from the plurality of FIR filters;and a signal representative of a directionless wireless signal formedfrom the summed signals.
 69. Th system of claim 68 wherein the samplingcircuits, the plurality of programmable FIR filters and the summingcircuit are formed on a single integrated circuit.
 70. The system ofclaim 68 further comprising a multiplier connected to each samplingcircuit to generate an in-phase channel and a quadrature channel, eachchannel being connected to a filter, a converter and one of the FIRfilters.
 71. The system of claim 68 wherein the communication systemcomprises a cellular network including a plurality of transceivers thatcommunicate by wireless link with mobile transceiver units, and furtherincluding a base station having an adaptive array processor providingweighting signals to the FIR filters.
 72. A cellular communicationsystem comprising: a first transceiver at a base station, the firsttransceiver and having a first processor and a first directionalantenna; a second transceiver on a mobile unit, the second transceiverhaving a second processor and a second antenna; a locator on the mobileunit that determines a physical location of the second antenna; aspatially multiplexed communication link formed between the first andsecond transceivers, the link including a wireless beam from the firstantenna to the second antenna; and a first adaptive programmablebeamformer circuit in the first transceiver that shapes the wirelessbeam to be directed between the first antenna and the second antenna,the first adaptive programmable beamformer circuit having a steeringcircuit for adjusting a plurality of weights to the programmablebeamformer circuit, the programmable beamformer circuit having aplurality of sampling circuits for receiving communication signals, anda single integrated chip having a plurality of complex multipliers, aplurality of down conversion circuits and a plurality of programmablefinite impulse response (FIR) filters, each FIR filter being connectedto a down conversion circuit.
 73. A cellular communication system ofclaim 72, wherein the plurality of sampling circuits for receivingcommunication signals, the plurality of complex multipliers, theplurality of down conversion circuits and the plurality of FIR filterscomprise an integrated circuit.